The present invention relates to the field of semiconductor circuits and more particularly to a comparator circuit.
A comparator circuit is utilized for many applications. In general a comparator receives two inputs and generates an output based on the comparison of the two input signals. The comparison is typically looking at the amplitude or magnitude of the input voltages. A differential voltage magnitude comparator is a type of a comparator in which two differential input signals are provided to the comparator and a differential output is generated from the comparator. In one application one of the differential inputs is a reference signal. For example if the reference signal is a steady state voltage value the reference input then can be used to elevate the signal level of one of the other differential inputs for performing the comparison.
For example, a differential comparator can be used to detect squelch (or unsquelch) for a receiver coupled to receive an input signal. For example, such a receiver can be coupled to a communication line or bus to discern when valid traffic is present on the line. When the traffic is sent over a single differential pair the presence of valid traffic is defined by the voltage difference between the pair of data lines comprising the differential pair. The state in which traffic is present is defined as the unsquelch state while the absence of traffic is defined as the squelch state. A comparator circuit can be used to identify the squelch/unsquelch states.
The present invention provides for a differential voltage magnitude comparator in which one of the applications of the comparator of the present invention is to perform the squelch/unsquelch detection.